Nucleic acid (DNA, RNA, PNA) aptamers that specifically bind to their target substances have been studied for their biotechnological application and pharmaceutical application as biological substances capable of recognizing molecules alternative to antibodies. As methods of obtaining these nucleic acid aptamers, SELEX (Systematic Evolution of Ligands by Exponential Enrichment) method has been known. For example, it is known that nucleic acid aptamers that specifically bind to a target substance are able to be found by carrying out screening of a mixture (library) of a large number of nucleic acid molecules having random sequence.
Meanwhile, there are also many reports about examples of use of the nucleic acid aptamer as a pharmaceutical. For example, Patent Document 1 discloses an invention of an RNA aptamer having a specific nucleotide sequence and reports that the RNA aptamer specifically binds to hirame rhabdovirus (HIRRV) or a polypeptide expressed in the virus to function to inhibit the ability of the virus to infect a host.
In addition, Patent Document 2 discloses an invention of nucleic acid aptamer (artificial nucleic acid molecule) that specifically binds to camptothecins such as irinotecan or topotecan and reports that a modified nucleoside structure in which a purine structure is linked to a thymidine moiety (which binds to the C5 position) via a carbon chain produces excellent binding affinity.